Module with reversely coupled inductors and magnetic molded compound (MMC)

ABSTRACT

A device includes a first inductor and a second inductor reversely coupled with the first inductor, wherein the first and second inductors have overlapping windings. The device also includes a housing for the first and second inductor, wherein the housing is filled with a magnetic molding compound.

BACKGROUND

An inductor is a passive two-terminal device that stores energy in amagnetic field when current passes through the inductor. An exampleinductor includes an insulated conductor wrapped around a core. Oneexample use of an inductor is at the output of a buck converter to storeenergy. The design of the inductor is not trivial and affects losses dueto the intrinsic resistivity of the conductor material andfrequency-dependent losses such as core-material losses (magnetichysteresis loss, eddy-current loss), skin-effect losses in the conductor(current displacement at high frequencies), magnetic-field losses ofadjacent windings (proximity effect), and radiation losses.

In a multi-phase converter, a plurality of converter circuits, each withits own output inductor, are docked at different phases and the outputsfrom the plurality of converter circuits are combined. With amulti-phase converter, the amount of ripple in the converter output isreduced compared to single phase converters. Again, the design ofinductors used in a multi-phase converter is not trivial.

SUMMARY

In accordance with at least one example of the disclosure, a devicecomprises a first inductor and a second inductor reversely coupled withthe first inductor, wherein the first and second inductors haveoverlapping windings. The device also comprises a housing for the firstand second inductor, wherein the housing is filled with a magneticmolding compound.

In accordance with at least one example of the disclosure, a methodcomprises arranging a first inductor and a second inductor in areversely coupled configuration, wherein the first and second inductorshave overlapping windings. The method also comprises positioning thefirst and second inductors in a housing. The method also comprisesfilling the housing with a magnetic molding compound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a multi-phase converter inaccordance with various examples.

FIG. 2 is a graph showing switch node signals of a multi-phase converterin accordance with various examples.

FIGS. 3A-3F are different views of a reversely coupled inductor modulein accordance with various examples.

FIGS. 4A-4I show an assembly process for the reversely coupled inductormodule of FIGS. 3A-3F.

FIGS. 5A-5B are different views of an inductor module in accordance withvarious examples.

FIG. 5C is a graph showing current density for the inductor module ofFIGS. 5A and 5B.

FIG. 5D is a graph showing the magnetic flux density for the inductormodule of FIGS. 5A and 5B.

FIGS. 6A-6B are different views of the reversely coupled inductor moduleof FIGS. 3A-3F in accordance with various examples.

FIG. 6C is a graph showing current density for the reversely coupledinductor module of FIGS. 6A and 6B.

FIG. 6D is a graph showing the magnetic flux density for the reverselycoupled inductor module of FIGS. 6A and 6B.

FIGS. 7A-7D are different views of a reversely coupled inductor modulein accordance with various examples.

FIG. 8A is a cross-sectional view of the reversely coupled inductormodule related to FIGS. 7A-7D.

FIG. 8B is a graph showing the magnetic field strength for the reverselycoupled inductor module of FIGS. 7A-7D.

FIGS. 9A-9R show an assembly process for the reversely coupled inductormodule of FIGS. 7A-7D in accordance with various examples.

FIGS. 10A-10F show different reversely coupled inductor module optionsin accordance with various examples.

FIGS. 11A-11P show another assembly process for a reversely coupledinductor module in accordance with various examples.

DETAILED DESCRIPTION

Described herein are modules with reversely coupled inductors andmagnetic molded compound (MMC). In some examples, a module includes afirst inductor and a second inductor reversely coupled with the firstinductor, wherein the first and second inductors have overlappingwindings. The module also comprises a housing for the first and secondinductor, wherein the housing is filled with MMC. In different examples,the first and second inductors are symmetrical or asymmetrical. Also, indifferent examples, magnetic cores are used or are omitted. When used,the shape and/or orientation of the magnetic core varies. As usedherein, an “inductor” refers to a component with two terminals and atleast one winding coupled between the two terminals. As an option, aninductor includes a magnetic core. As used herein, “coupled inductors”are different than transformers because the coupling coefficient isgenerally less than a transformer. An example coupling coefficient forcoupled inductors in 90% or less. Meanwhile, an example couplingcoefficient for a transformer is higher than 95%.

In some examples, to assemble a module with reversely coupled inductorsand MMC, a module base with terminals or contacts is used, where thefirst and second inductors are coupled to the module base. In someexamples, a die with multi-phase converter circuitry is also includedwith or coupled to the module base. In some examples a non-magneticmolding material is positioned between the module base and theoverlapping windings of the first and second inductors. In someexamples, a magnetic core is positioned in the center of the overlappingwindings of the first and second inductors. In different examples, partsof the first and second inductors are positioned relative to a magneticcore with an H-shape or T-shape. After the first and second inductorsare coupled to the module base with any magnetic core and/ornon-magnetic molding material in place, MMC is added. In some examples,a housing is used, where MMC fills the available space between andaround components of the module and the housing. The housing used toshape the MMC is either permanent or temporary.

With the described modules, the distributed air gaps in MMC absorbsdirect-current bias fields, reduces electromagnetic interference (EMI),and reduces a fringing effect. Also, with the overlapping windings ofthe first and second inductors, high inductance density and strongcoupling with the same current direction is achieved. In some examples,the current direction is the same from the terminal point of view, butis not always the same inside the module. For at least some describedmodules, the coupling coefficient between phases in the range of 20%-80%(stronger than non-coupled inductors and weaker than transformers). Asdesired, a magnetic core is added to increase an inductance densityand/or a coupling coefficient. In some examples, the modules aredesigned to achieve a target reverse coupling (e.g., at least 20%), aphase current ripple that is less than a target threshold, and transientperformance that has a target threshold for overshoot, undershoot,setting time, etc.

In some described modules, a coupled inductor working in a two-phasebuck converter has two equivalent inductances: a steady-state inductanceL_(ss), which impacts the steady state phase current ripple (a largerL_(ss) value is targeted in some examples) and a transient inductanceL_(tr), which impacts the load transient response (a smaller L_(tr)value is targeted in some examples). For a given set of inductors, theL_(ss) and L_(tr) is determined by the inductor structures andmaterials, and the L_(ss) and L_(tr) values are characterized by theinductor current waveform during steady state operation and loadtransient condition. In the described modules, a reversely coupledinductor has a desired feature (L_(ss)>L_(tr)) so that a small steadystate phase current and a fast transient response can be achievedtogether. To provide a better understanding, various options for moduleswith reversely coupled inductors and MMC are described using the figuresas follows.

FIG. 1 is a schematic diagram showing a multi-phase converter 100 inaccordance with various examples. As shown, the multi-phase converter100 includes a first buck converter circuit 102 with switches, S1 andS2, coupled between a supply voltage node 106 (to provide Vin) and aground node. More specifically, Vin is maintained by an input capacitor,Cin, which is represented as separate from the first buck convertercircuit 102. In FIGS. 1, S1 and S2 are represented as NMOS transistorswith respective control terminals and current terminals, where each ofS1 and S2 have a diode across their respective current terminals. Inother examples, the components and/or arrangement of components for S1and S2 may vary. Between S1 and S2 is a switch node 108, where an outputinductor (L1) for the first buck converter circuit 102 has one sidecoupled to the switch node 108. The other side of L1 is coupled to anoutput node 110 for the multi-phase converter 100.

As shown, the multi-phase converter 100 also includes a second buckconverter circuit 104 with switches, S3 and S4, coupled between thesupply voltage node 106 (to provide Vin) and a ground node. Again, Vinis maintained by Cin, which is represented as separate from the secondbuck converter circuit 104. In FIGS. 1, S3 and S4 are represented asNMOS transistors with respective control terminals and currentterminals, where each of S3 and S4 have a diode across their respectivecurrent terminals. Between S3 and S4 is a switch node 112, where anoutput inductor (L2) for the second buck converter circuit 104 has oneside coupled to the switch node 112. The other side of L2 is coupled tothe output node 110 for the multi-phase converter 100.

In FIG. 1, the outputs from the first and second buck converters 102 and104 are combined at the output node 110 (resulting in Vout) and providedto an output capacitor, Cout, for use by a load, which draws a current(ILoad). As represented in FIG. 1, the multi-phase converter 100 mayinclude additional buck converters. To reduce output ripple in Vout, theswitches of each of the buck converters are operated at differentphases. Also, in some examples, L1 and L2 are provided using a modulewith reversely coupled inductors and MMC as described herein. With theproposed modules, output inductors such as L1 and L2 achieve targetperformance criteria such as a target reverse coupling (e.g., at least20%), a phase current ripple that is less than a target threshold, andtransient performance that has a target threshold for overshoot,undershoot, setting time, etc.

FIG. 2 is a graph 200 showing switch node signals 202 and 204 of amulti-phase converter in accordance with various examples. In graph 200,the switch node signal 202 corresponds to a first phase (phase 1) ofenergy provided to L1 by the operations of the first buck converter 102in FIG. 1. Meanwhile, the switch node signal 204 corresponds to a secondphase (phase 2) of energy provided to L2 by the operations of the secondbuck converter 104 in FIG. 1. By offsetting phase 1 and phase 2 of amulti-phase converter such as the multi-phase converter 100 of FIG. 1,output voltage (Vout) ripple is reduced.

FIGS. 3A-3F are different views of a reversely coupled inductor module300 in accordance with various examples. As shown in FIG. 3A, the module300 includes a base (e.g., a leadframe base) 302. Attached to the base302 are side contacts 304A-304D (only side contacts 304A-304C arevisible in FIG. 3A) for a first inductor 306 and a second inductor 308.More specifically, the side contacts 304B and 304C are coupled to sideterminals of the first inductor 306, while the side contacts 304A and304D are coupled to side terminals of the second inductor 308. Also, MMC310 fills the space around the first and second inductors 306 and 308.In operation, a current 312 flows through the side contacts 304B and304C and through the first inductor 306 in a given direction. Also, acurrent 311 flows through the side contacts 304A and 304D and throughthe second inductor 308 in the same direction as the current 312 at theterminals of the module 300. In the example of FIG. 3A, the dimensionsof the module 300 is 4 mm×3 mm×2.5 mm. In other examples, the dimensionsfor a module such as the module 300 vary in one or more dimensions.

In FIG. 3B, the first and second inductors 306 and 308 are described ingreater detail. More specifically, the first inductor 306 is amulti-level winding that includes a primary winding 314 with an upperwinding extension 316A and a lower winding extension 316B, where each ofthe upper winding extension 316A and the lower winding extension 316Bhas a curved (e.g., hook) shape. Similarly, the second inductor 308 is amulti-level winding that includes a primary winding 318 with an upperwinding extension 320A and a lower winding extension 320B, where each ofthe upper winding extension 320A and the lower winding extension 320Bhas a curved (e.g., hook) shape. FIG. 3C shows a close up view of thefirst inductor 306 with the primary winding 314, the upper windingextension 316A, and the lower winding extension 316B. In some examples,the second inductor 308 has the same shape as the first inductor 306,and is oriented 180 degrees opposite of the first inductor 306. When thefirst and second inductors 306 and 308 are assembled as represented inFIG. 3B, the upper and lower winding extensions 316A and 316B of thefirst inductor 306 wrap around the primary winding 318 of the secondinductor 308. Meanwhile, the upper and lower winding extensions 320A and320B of the second inductor 308 wrap around the primary winding 314 ofthe first inductor 306. With the arrangement represented in FIG. 3B, thefirst and second inductors 306 and 308 are described herein as havingoverlapping windings in the form of a multi-level entangled arrangementor multi-level embrace arrangement.

FIG. 3D shows a cross-sectional view of the module 300 of FIG. 3A. InFIG. 3D, the primary winding 314, the upper winding extension 316A, andthe lower winding extension 316B of the first inductor 306 is shownrelative to the primary winding 318, the upper winding extension 320A,and the lower winding extension 320B of the second inductor 308. Also inFIG. 3D, the base 302, the side contacts 304C and 304D, and the MMC 310are represented.

FIG. 3E shows a top view of some components of the module 300. In FIG.3E, portions of the primary winding 314, the upper winding extension316A, and the lower winding extension 316B of the first inductor 306 arevisible. Also, portions of the primary winding 318, the upper windingextension 320A, and the lower winding extension 320B of the secondinductor 308 are visible. Also, the side contacts 304A-304D are visible.

FIG. 3F shows another top view of some components of the module 300. InFIG. 3F, the primary winding 314, the upper winding extension 316A, andthe lower winding extension 316B of the first inductor 306 are visiblealong with side contacts 304B and 304C. As can be understood from FIGS.3E and 3F, when the first and second inductors 306 and 308 are assembledfor the module 300 and are viewed from the top, part of lower windingextension 316B of the first inductor 306 is covered by the upper windingextension 320A of the second inductor 308. Likewise, part of the lowerwinding extension 316B of the first inductor 306 is covered by the upperwinding extension 320A of the second inductor 308.

FIGS. 4A-4F show an assembly process 400 for the reversely coupledinductor module 300 of FIGS. 3A-3F. In step 402 of FIG. 4A, the firstand second inductors 306 and 308 are obtained. As shown, the firstinductor 306 initially includes the primary winding 314 with upper andlower winding extensions 316A and 316B that are straight. Likewise, thesecond inductor 308 initially includes the primary winding 318 withupper and lower winding extensions 320A and 320B that are straight. Instep 404 of FIG. 4B, the first and second inductors 306 and 308 arepositioned relative to each other such that axis of the primary winding314 of the first inductor 306 is parallel with the axis of the primarywinding 318 of the second inductor 308. Also, the upper windingextension 316A of the first inductor 306 passes over and in the oppositedirection of the lower winding extension 320A of the second inductor308. Also, the upper winding extension 32A of the second inductor 306passes over and in the opposite direction of the lower winding extension318B of the first inductor 306.

In step 406 of FIG. 4C, the upper and lower winding extensions 316A and316B of the first inductor 306 are wrapped around primary winding 318 ofthe second inductor 308. Also, the upper and lower winding extensions320A and 320B of the second inductor 308 are wrapped around primarywinding 314 of the first inductor 306. After step 406 is complete, thefirst and second inductors 306 and 308 have overlapping windings. Instep 408 of FIG. 4D, the first and second inductors 306 and 308 (withoverlapping windings) are coupled to the side contacts 304A-304D. Instep 410 of FIG. 4E a base (e.g., with an integrated circuit die 411) isobtained. At step 412 of FIG. 4F, the side contacts 304 are coupled tothe base 302. As shown, in some examples, the base 302 includes or iscoupled to an integrated circuit die 411. In step 414 (represented byviews 414A-414C in FIGS. 4G, 4H, and 4I), MMC 310 is added around thefirst and second inductors 306 and 308. In some examples, adding the MMC310 results in the module 300 having a solid rectangular shape, wherethe first and second inductors 306 and 308 are embedded in the MMC 310.

FIGS. 5A-5B are different views of an inductor module in accordance withvarious examples. In view 500 of FIG. 5A, a module 501 with parallelinductors 502 and 504 with no overlapping windings is represented. Inview 510 of FIG. 5B, a cross-sectional view of the module 501 with theparallel inductors 502 and 504 is represented.

FIG. 5C is a graph 520 showing current density for the inductor module500 of FIGS. 5A and 5B. As shown in graph 520, higher current densitylevels are located in the inner windings of the parallel inductors 502and 504. FIG. 5D is a graph 530 showing the magnetic flux density forthe inductor module 501 of FIGS. 5A and 5B. As shown in graph 530, themagnetic flux density is concentrated in the interior of the windingsfor the parallel inductors 502 and 504.

FIGS. 6A-6B are different views 600 and 610 of the reversely coupledinductor module 300 of FIGS. 3A-3F in accordance with various examples.In view 600 of FIG. 6A, the module 300 includes the reversely coupledinductors 306 and 308. In view 610 of FIG. 6B, a cross-sectional view ofthe module 300 with the reversely coupled inductors 306 and 308 isrepresented.

FIG. 6C is a graph 620 showing current density for the reversely coupledinductor module 300 of FIGS. 6A and 6B. As shown, in graph 620, currentdensity levels for the module 300 are lower than for the module 501,resulting in lower winding losses in module 300 compared to module 501.FIG. 6D is a graph 630 showing the magnetic flux density for theinductor module 300 of FIGS. 6A and 6B. As shown in graph 630, themagnetic flux density is concentrated in the interior of the primarywindings for the reversely coupled inductor modules 306 and 308, and islower intensity than the magnetic flux density represented for theinductor module 501 in graph 530, resulting in lower core losses inmodule 300 compared to module 501.

FIGS. 7A-7D are different views of a reversely coupled inductor module700 in accordance with various examples. As shown in FIG. 7A, the module700 includes a base (e.g., a leadframe base) 702. Attached to the base702 are a first inductor 704 and second inductor 706 with overlappingwindings, where a magnetic core 708 is used. Also, MMC 710 fills thespace around the first inductor 704, the second inductors 706, and themagnetic core 708. In operation, a first current 311 flows through thefirst inductor 704, and a second current 312 flows through the secondinductor 706, where the first and second currents 311 and 312 flow inthe same direction. In the example of FIG. 7A, the dimensions of themodule 700 is 8 mm×7 mm×4.5 mm. In other examples, the dimensions for amodule such as the module 700 vary in one or more dimensions.

FIG. 7B is a perspective view of the magnetic core 708. As shown, themagnetic core 708 includes an upper portion 720, a middle portion 722,and a lower portion 724. When viewed from the side as in FIG. 7D, theupper portion 720, the middle portion 722, and the lower portion 724 ofthe magnetic core 708 form an H-shape. In the example of FIG. 7B, thelower portion 724 includes corner gaps or cut-outs 726 to enablematerial of the first and second inductors 704 and 706 to pass throughthe corner gaps 726 as represented in FIG. 7A.

In FIG. 7C, a side view that includes the magnetic core 708 and thefirst and second inductors 704 and 706 is represented. In the examplerelated to FIGS. 7A and 7C, the first inductor 704 includes anoverlapping extension 730A, two middle extensions 730B, and two baseextensions 730C. Similarly, the second inductor 706 includes anoverlapping extension 732A, two middle extensions 732B, and two baseextensions 732C. In some examples, each of the overlapping extensions730A and 732A has a flat U-shape (best seen in FIG. 7A), where theoverlapping extension 730A of the first inductor 704 is oriented 180degrees opposite from the overlapping extension 732A of the secondinductor 706. For the first inductor 704, the two middle extensions 730Band the two base extensions 730C extend from opposite sides of theU-shaped overlapping extension 730A. Similarly, for the second inductor706, the two middle extensions 732B and the two base extensions 732Cextend from opposite sides of the U-shape overlapping extension 732A.

In the example of FIG. 7C, the base extensions 730C of the firstinductor 704 and the base extensions 732C of the second inductor 706 arepositioned between the base 702 and the lower portion 724 of themagnetic core 708. Meanwhile, the middle extensions 730B of the firstinductor 704 and the middle extensions 730B of the second inductor 706extend through the corner gaps 726 in the lower portion 724 of themagnetic core 708 to the area around the middle portion 722. In theexample of FIGS. 7A-7D, the middle extensions 730B of the first inductor704 is longer than the middle extensions 732B of the second inductor 706(the first and second inductors 704 and 706 are asymmetric) tofacilitate fitting the overlapping extensions 730A and 732A between theupper and lower portions 720 and 724 of the magnetic core 708. With thearrangement represented in FIGS. 7A and 7C, the first and secondinductors 704 and 706 are described herein as having overlappingwindings in the form of a stacked arrangement (the overlapping extension730A of the first inductor 704 is stacked on the overlapping extensions732A of the second inductor 706).

FIG. 8A is a cross-sectional view 800 of the reversely coupled inductormodule 700 related to FIGS. 7A-7D. In the cross-sectional view 800, theH-shape of the magnetic core 708 is visible. Again, the H-space of themagnetic core 708 is formed by the upper portion 720, the middle portion722, and the lower portion 724 of the magnetic core 708. Also, in thecross-sectional view 800, the overlapping extension 730A, one middleextension 730B, and one base extension 730C of the first inductor 704are visible. Also, the overlapping extension 732A, one middle extension732B, and one base extension 732C of the second inductor 706 arevisible. Also, in the cross-sectional view 800, the base 702 and the MMC710 for the module 700 are represented. FIG. 8B is a graph 810 showingthe magnetic field strength for the reversely coupled inductor module700 related to FIGS. 7A-7D. As shown in graph 810, the distributed airgaps in MMC 710 absorbs most of the magnetic field strength induced bythe direct-current bias.

FIGS. 9A-9R show an assembly process 900 for the reversely coupledinductor module 700 of FIGS. 7A-7D in accordance with various examples.The process 900 of FIG. 9 starts at step 902 (represented in FIGS.9A-9C) with obtaining the magnetic core 708. More specifically, FIG. 9Ais a perspective view of the magnetic core 708, FIG. 9B is a side viewof the magnetic core 708, and FIG. 9C is a top view of the magnetic core708. At step 904 (represented in FIGS. 9D-9F), the second inductor 706is positioned relative to the magnetic core 708. As described above inconnection with FIGS. 7A-7D and as depicted in FIGS. 9D-9F, theoverlapping extension 732A for the second inductor 706 has a flatU-shape, where the U-shape fits around the middle portion 722 of themagnetic core 708. In some examples, the middle extensions 732B and thebase extensions 732C are bent around the lower portion 724 of themagnetic core 708 after the overlapping extension 732A is in placearound the middle portion 722. At step 906 (represented in FIGS. 9G-9I),the first inductor 704 is positioned relative to the magnetic core 708and the second inductor 706. As described above in connection with FIGS.7A-7D and as depicted in FIGS. 9G-9I, the overlapping extension 732A forthe second inductor 706 has a flat U-shape, where the U-shape fitsaround the middle portion 722 of the magnetic core 708. In someexamples, the middle extensions 730B and the base extensions 730C of thefirst inductor 704 are bent around the lower portion 724 of the magneticcore 708 after the overlapping extension 730A is in place around themiddle portion 722 and above the overlapping extension 732A of thesecond inductor 706.

At step 908 (represented in FIGS. 9J-9L), the base 702 is obtained. Inthe example of FIGS. 9J-9I, the base 702 includes or is coupled to anintegrated circuit die 713 (e.g., with multi-phase converter componentssuch as the components described in FIG. 1). More specifically, FIG. 9Jis a perspective view of the base 702 with the integrated circuit die713, FIG. 9K is a side view of the base 702 with the integrated circuitdie 713, and FIG. 9I is a top view of the base 702 with the integratedcircuit die 713. At step 910 (represented in FIGS. 9M-9O), the assemblyincluding the magnetic core 708, the second inductor 706, and the firstinductor 704 are attached to the base 702. At step 912 (represented inFIGS. 9P-9Q), MMC 710 is applied to the assembly of the base 702, themagnetic core 708, the second inductor 706, and the first inductor 704.

FIGS. 10A-10F show different reversely coupled inductor module optionsin accordance with various examples. In FIGS. 10A and 10B, a module 1000with a base 1002, a first inductor 1030, a second inductor 1032, amagnetic core 1008, and MMC 1010 is represented. For the module 1000,the first and second inductors 1030 and 1032 are symmetric. Morespecifically, the first inductor 1030 includes an overlapping extension1034A, two middle extensions 1034B, and two base extensions 1034C.Similarly, the second inductor 1032 includes an overlapping extension1036A, two middle extensions 1036B, and two base extensions 1036C. Incontrast to the first and second inductors 704 and 706 described for themodule 700, each of the overlapping extension 1034A and 1036A for thefirst and second inductors 1030 and 1032 has a ramped U-shape. Also, forthe module 1000, the magnetic core 1008 has a T-shape with an upperportion 1012 and a stem portion 1014, where the stem portion 1014extends between the overlapping extensions 1034A and 1036A of the firstand second inductors 1030 and 1032, and where the upper portion 1012 ofthe magnetic core 1008 is above the first and second inductors 1030 and1032. With the arrangement represented in FIGS. 10A and 10B, the firstand second inductors 1030 and 1032 are described herein as havingoverlapping windings in the form of a dual-ramp arrangement (theoverlapping extension 1034A of the first inductor 1030 and theoverlapping extensions 1036A of the second inductor 1032 are bothramped).

In FIGS. 10C and 10D, a module 1016 with the base 702, the firstinductor 704, the second inductor 706, the magnetic core 1008, and MMC1010 is represented. As described above in connection with FIGS. 7A-7D,the first and second inductors 704 and 706 are asymmetric (due to themiddle extensions 730B of the first inductor 704 being longer than themiddle extensions 732B of the second inductor 706). In contrast to theramped U-shape of the overlapping extensions 1034A and 1036A of thefirst and second inductors 1030 and 1032 described for the module 1000,the overlapping extensions 730A and 732A of the first and secondinductors 704 and 706 have a flat U-shape. The module 1016 of FIGS. 10Cand 10D differ from the module 700 of FIGS. 7A-7D at least because themagnetic core 1008 has a T-shape. More specifically, the T-shape for themagnetic core 1008 includes an upper portion 1012 and a stem portion1014, where the stem portion 1014 extends between the overlappingextensions 730A and 732A of the first and second inductors 704 and 706,and where the upper portion 1012 of the magnetic core 1008 is above thefirst and second inductors 704 and 706.

In FIGS. 10E and 10F, a module 1018 with the base 702, the firstinductor 704, the second inductor 706, a magnetic core 1009, and MMC1010 is represented. As described above in connection with FIGS. 7A-7D,the first and second inductors 704 and 706 are asymmetric (due to themiddle extensions 730B of the first inductor 704 being longer than themiddle extensions 732B of the second inductor 706). The module 1018 ofFIGS. 10E and 10F differ from the module 700 of FIGS. 7A-7D at leastbecause the magnetic core 1008 has a T-shape. More specifically, theT-shape for the magnetic core 1009 includes an upper portion 1013 and astem portion 1015, where the stem portion 1015 extends between theoverlapping extensions 730A and 732A of the first and second inductors704 and 706, and where the upper portion 1013 of the magnetic core 1009is below the overlapping extensions 730A and 732A of the first andsecond inductors 704 and 706. In some examples, the magnetic core 1009has corner gaps or cut-outs 1017 in the upper portion 1013 to facilitatepositioning the middle extensions 730B and 732B of the first and secondinductors 704 and 706 relative to the magnetic core 1009.

FIGS. 11A-11P shows another assembly process 1100 for a reverselycoupled inductor module in accordance with various examples. As shown,the process 1100 includes obtaining a plurality of leadframe terminals1102 at step 1140 (represented in FIGS. 11A and 11B). In some examples,the leadframe terminals 1102 have a height of 0.2 mm. At step 1142(represented in FIGS. 11C and 11D), an integrated circuit die 1104 iscoupled to the leadframe terminals 1102. In some examples, thefour-terminal leadframe represented in FIGS. 11C and 11D is not a finaldesign of the leadframe for the respective module. The four terminals1102 represented in FIGS. 11C and 11D are only for the coupledinductors. In some examples, additional traces and layouts are used toensure the integrated circuit die 1104 operates properly. At step 1144(represented in FIGS. 11E and 11F), molding 1106 is applied to cover theintegrated circuit die 1104. Also, standoffs 1108 are added to or areformed with the molding 1106 during step 1144.

At step 1146 (represented in FIGS. 11G and 11H), a second inductor 1132that includes an overlapping extension 1136A (e.g., a flat U-shape) andtwo contact extensions 1136B is coupled to two of the leadframeterminals 1102 (e.g., the two contact extensions 1136B are coupled totwo of the leadframe terminals 1102). In FIGS. 11G and 11H, theoverlapping extension 1132A of the second inductor 1132 is separatedfrom the integrated circuit die 1104 by the molding 1106 and/or thestandoffs 1108. The second inductor 1132 is different than the secondinductor 706 in FIGS. 7A-7D at least because there are no baseextensions for the second inductor 1132. At step 1148 (represented inFIGS. 11I and 11J), a first inductor 1130 that includes an overlappingextension 1134A (e.g., a flat U-shape) and two contact extensions 1134Bis coupled to the other two leadframe terminals 1102 (e.g., the twocontact extensions 1134B are coupled to the two leadframe terminals 1102still available after the second inductor 1132 is coupled to two of theleadframe terminals 1102). As represented in the views provided in FIGS.11I and 11J, the overlapping extension 1134A of the first inductor 1130is positioned over the overlapping extension 1136A of the secondinductor 1132 in step 1148, where the orientation of the overlappingextensions 1134A of the first inductor 1130 and the overlappingextension 1136A of the second inductor 1130 is 180 degrees oppositerelative to each other. Also, the first inductor 1130 is different thanthe first inductor 704 in FIGS. 7A-7D at least because there are no baseextensions for the first inductor 1130.

In some examples, the process 1100 proceeds from step 1148 to step 1150(represented in FIGS. 11K and 11L), where MMC 1110 is applied around thefirst and second inductors 1130 and 1132. In other examples, the process1100 proceeds from step 1148 to step 1152 (represented in FIGS. 11M and11N), where a magnetic core 1118 is inserted between the overlappingportion 1134A of the first inductor 1130 and the overlapping portion1136A of the second inductor 1132. At step 1154 (represented in FIGS.11O and 11P), MMC 1110 is applied around the first inductor 1130, thesecond inductor 1132, and the magnetic core 1118.

In this description, the recitation “based on” means “based at least inpart on.” Therefore, if X is based on Y, then X may be a function of Yand any number of other factors.

Modifications are possible in the described embodiments, and otherembodiments are possible, within the scope of the claims.

What is claimed is:
 1. A module, comprising: a first inductor; a secondinductor reversely coupled with the first inductor; and a housing inwhich the first and second inductors are positioned, the housing filledwith a magnetic molding compound; each of the first and second inductorscomprising a respective primary winding having upper and lower windingextensions, in which the first and second inductors have overlappingwindings that comprise: the upper and lower winding extensions of thefirst inductor wrapped around the primary winding of the secondinductor; and the upper and lower winding extensions of the secondinductor wrapped around the primary winding of the first inductor. 2.The module of claim 1, further comprising a die coupled to the first andsecond inductors, the die comprising multi-phase power convertercomponents.
 3. The module of claim 2, further comprising a moldingmaterial separate from the magnetic molding material, the moldingmaterial between the die and the overlapping windings.
 4. A method,comprising: arranging a first inductor and a second inductor in areversely coupled configuration; positioning the first and secondinductors in a housing; and filling the housing with a magnetic moldingcompound; each of the first and second inductors comprising a respectiveprimary winding having upper and lower winding extensions, in which thefirst and second inductors have overlapping windings, and arranging thefirst inductor and the second inductor in the reversely coupledconfiguration comprises: wrapping the upper and lower winding extensionsof the first inductor around the primary winding of the second inductor;and wrapping the upper and lower winding extensions of the secondinductor around the primary winding of the first inductor.
 5. The methodof claim 4, further comprising coupling the first and second inductorsto a die comprising multi-phase power converter components.
 6. Themethod of claim 5, further comprising adding a molding material betweenthe die and the overlapping windings, the molding material separate fromthe magnetic molding material.